1. Field of the Invention
This invention relates to a three dimensional display system and, more specifically, to a system for transferring and projecting a three dimensional image onto a screen or into space remote from the original three dimensional image.
2. Brief Description of the Prior Art
In accordance with the above noted copending application, a disk-like screen is connected to the end of a motor shaft. The disk is attached to the shaft of a motor at a 45 degree angle or compound helix shape, though this angle can be varied to provide a larger or smaller height or z-axis dimension, so that, as the disk rotates, a displacement of any given point thereon along the z-axis takes place. The image is formed on the screen by projecting a light beam, such as from a laser, through a modulator and toward a scanner which produces an x-y scan of the beam on a screen, the screen being the disk discussed hereinabove. The disk can be translucent, such as lucite, so that images can be projected thereon onto the front and/or rear surfaces thereof. The modulation or strobing of the scan is then synchronized with the rotating disk by control of the motor speed so that a three dimensional pattern appears on the screen. It can be seen that any point on the x-y scan from the scanner which impinges upon the screen will move along a z-axis direction since the screen or disk at that point produces such z-axis movement. This movement of the displayed image provides the three dimensional effect. The adjustment of the angle between the disk surface and the x-y plane of the scanned x-y image will determine the z-dimension or height of the three dimensional image, the disk angle being adjustable on-line, if so desired.
While the disk is a planar opaque screen for receiving a scanned image thereon on one surface thereof, the screen can take many other forms. For example, the disk can be translucent, such as lucite, and thereby be capable of receiving a scanned image thereon on both major surfaces. The lucite disk can be in the form of a pair of angularly truncated cylinders with the same truncation angle which fit together at the angularly truncated surfaces to form a new cylinder wherein the surfaces at which truncation takes place are translucent. In addition, the screen can take on shapes other than planar, it merely being necessary that at least some portion thereof move in the z-direction during rotation thereof while projection of the x-y image thereon takes place to provide the three dimensional image. As a further embodiment, the disk can be placed in a gas filled or evacuated CRT with the image impinging thereon being the scanned beam of the tube. Phosphors can be disposed on the disk which, when excited, will form the three dimensional image. As a still further embodiment, the screen can be planar and disposed normal to the projected x-y image. The three dimensional affect is then provided by moving the entire screen along the z-axis in synchronism with the scanned x-y image to provide the three dimensional affect. A cam driven shaft attached to the screen can provide such screen movement along the z-axis.
While the above described prior system provides a highly effective three-dimensional display, the fact that the display is so closely positioned with respect to the rapidly rotating disk makes it undesirable and dangerous for observers to be located close to the display. In addition, the display cannot be readily observed when the ambient light is significant. Accordingly, for example, if the system were to be used in the cockpit of an airplane and sunlight were to enter the cockpit, viewing of the display would be difficult if not impossible. It is therefore also the desire to provide a three dimensional display of the type described in the above noted copending application which can be viewed under almost any type of ambient light conditions.